NFC Power State Detection via Inductive Energy Harvesting
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Solution Overview
Problem
NFC devices such as air conditioners and microwaves face challenges in being powered on for network connectivity, as they often lack display or input functions necessary for wireless LAN settings, and existing solutions require user intervention to detect power states, which is inconvenient.
Innovation Solution
An NFC device equipped with an antenna unit, a first power source unit to generate power from received radio waves, a second power source unit, a power-supply state holding unit, and a power source switch unit that allows the NFC device to transmit its power state to a reader/writer, enabling detection even when the second power source is off, and switching to the first power source for activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the NFC device uses the second power source unit (drive power source) to operate, then the device can perform normal functions including NFC communication, but the device cannot detect or transmit its power state when the second power source is turned off to save energy
Solution Approach 1:
The power source system is segmented into two independent units: the second power source unit (drive power source) for normal device operation and the first power source unit (power detection power source) specifically for detecting and transmitting power state information. This segmentation allows the detection function to operate independently when needed, even when the main drive power source is turned off to save energy.
Solution Approach 2:
The first power source unit acts as an intermediary between the second power source unit and the reader/writer device. It detects the power state of the second power source unit and transmits this information to the reader/writer via NFC communication, enabling the reader/writer to determine whether the device is powered on without requiring the device to be fully operational.
2Reliability
If the NFC device remains powered on to enable reader/writer to detect power state, then communication is maintained, but energy is wasted when the device is not in use
Solution Approach 1:
Instead of maintaining continuous power on, the system uses periodic detection: the first power source unit is activated only when needed to detect and transmit power state information to the reader/writer. This allows the device to remain powered off for extended periods while still enabling communication about its power state when required.
Solution Approach 2:
The first power source unit autonomously detects the power state of the second power source unit and initiates NFC communication with the reader/writer to transmit this information without requiring user intervention or full device activation. The system serves itself by automatically managing power state detection and communication.
3Device complexity
If existing NFC devices without dedicated detection power source are used, then device complexity is reduced, but the ability to detect and transmit power state when drive power source is off is lost
Solution Approach 1:
The first power source unit serves multiple functions: it provides power to the NFC communication unit for transmitting power state information, detects the power state of the second power source unit, and enables the device to be identified by the reader/writer even when the main drive power source is off. This multi-functionality justifies the added complexity by providing comprehensive power state detection and communication capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables a reader/writer to obtain the power-supply state of an NFC device without user intervention, ensuring seamless communication and network connectivity even when the device is not actively powered on, improving usability and energy efficiency.
Implementation Method 1
an antenna unit (101) configured to receive radio waves from a reader/writer (20) by NFC
Implementation Method 2
a first power source unit (102) configured to generate power from the radio waves received by the antenna unit (101)
Data Source
AI summary
An NFC device according to the present invention includes the following units. An antenna unit receives radio waves from a reader/writer by NFC. A first power source unit generates power from the radio waves. A second power source unit is a drive power source. A power-supply state holding unit holds information indicating a power-supply state of the second power source unit. An NFC unit performs NFC via the antenna unit to transmit the information indicating the power-supply state of the second power source unit. A power source switch unit switches the second power source unit to the first power source unit according to the power-supply state of the second power source unit, in order to supply power to activate at least the NFC unit and the power-supply state holding unit.